Development is being pursued of electrically-powered vehicles such as electric vehicle, hybrid vehicle, and the like in which an electric motor for running the vehicle is driven by electric power from a power storage device which is typically a secondary battery. For these electrically-powered vehicles, it has been proposed to charge the vehicle-mounted power storage device by a power supply provided externally to the vehicle (the power supply will also be referred to simply as “external power supply” hereinafter). In the following, charging of a vehicle-mounted power storage device by means of an external power supply will also be referred to simply as “external charging.”
Japanese Patent Laying-Open No. 8-88908 (PTD 1) discloses a configuration of a charging device for charging a vehicle-mounted power storage device of an electrically-powered vehicle from a commercial power supply through an isolation transformer. As disclosed in PTD 1, it is preferable for the sake of safety to electrically isolate the vehicle-mounted power storage device and the external power supply from each other by the isolation transformer.
The charging device of PTD 1 has a configuration in which a diode arm is added to an inverter which is provided for running the vehicle. The diode arm and one arm of the inverter are used to convert AC power from the commercial power supply into DC power for charging the power storage device. In the configuration of PTD 1, the configuration of a component (inverter for running the vehicle) mounted on the electrically-powered vehicle is also used partially for external charging, to thereby enable the charging device to be downsized.